Anyone secondary glazed 30s lead windows - does it work & look good?

[loveyouradvice]

we;ve moved into 30s house with gorgeous leaded windows.... original ones from 30s with frames a bit rotten.

Most people round here seem to rip out and replace with double glazing, sometimes with metalwork reminiscent of 30s.

We're keen to refurbish and secondary glaze each window separately (so looks discreet)... Nice Polish guy today told us its possible but he's concerned there may be condensation between exterior and interior if ventilation not good.

Any thoughts on this - and whether it looks good when done? And how effective (or not) compared to double glazing?

Any pitfalls we've not thought of?

Not yet, but I'm looking at 30s properties and a mumsnet advanced search yields some v good reviews of secondary glazing in general and particularly these guys: www.stormwindows.co.uk/

condensation between glazing:

the essential point is to ventilate the space to the outside and not to the inside.

Outside air in the UK is generally cooler than inside air, and contains less water vapour.

It may be different if you are in Florida.

Some people make the mistake of thinking that the inside air is warmer so it will keep the glass dry. Not so.

Old windows are usually pretty gappy so it's not difficult to let them breathe to the outside. Seal or draughtstrip the inner /secondary pane as well as you can. Remember you will need at least one opening pane for ventilation. Perhaps a transom. Lack of ventilation will make your house damp.

If you have sealed external windows, you may need to drill one or more ventilation holes in the frame, sloping downward. Stuff them with a wisp of fibreglass insulation to keep insects and dust out. I've done some like this, and been very pleased with the results.